Modifiers matching grump:

• grouchy,
• covetous,
• greedy,
• condescending,
• wealthy,
• heartless,
• ill-tempered,
• miserly,
• grizzled,
• arrogant,
• mean,
• gruff,
• impatient,
• fastidious,
• misanthropic,
• jealous,
• rich,
• penny-pinching,
• principled,

Simple categories matching ill-tempered:

• tyrant,
• person,
• grump,